1. Field of the Invention
The present invention relates to the field of circuit cards and, more specifically, to a system and a method for removably connecting a circuit card to an associated substrate.
2. Description of the Prior Art
In one conventional construction of desk top computer systems and, specifically, of desk top personal computers, such personal computer includes an outer housing having a bottom wall on top of which the computer motherboard or system planar is horizontally mounted.
Within the interiors of their housings, modern personal computers are customarily provided with sheet metal cage structures adapted to receive and removably support at least one and preferably a plurality of options or extension cards which, when operatively installed in their associated cage structure upgrade the operating capabilities of the computer. These extension cards may be installed in the computer during its original manufacture and/or subsequently installed by the computer purchaser. Typical types of extension card include network, sound, graphic accelerator and multi-media cards.
An extension card is basically a relatively small rectangular printed circuit having along one side edge thereof, a connector edge portion that plugs into a corresponding socket portion of the cage structure to operatively couple the extension card to the motherboard or system planar of the computer.
Extending along one end edge portion of the extension card is a sheet metal connecting bracket having an outwardly bent securement tab portion positioned adjacent the side edge portion of the card opposite its connector edge portion. The tab portion rests upon an inturned side wall ledge of the cage structure and has notches formed therein that overlie and register with a spaced series of threaded circular openings defined in the ledge. The tab portion is removably secured to the ledge by a screw that extends through the tab notch and is threaded into its associated ledge opening. This securement of the tab portion to the cage structure ledge serves to anchor the installed extension card in place within the case structure, thereby preventing the connector edge portion thereof from being dislodged from its associated connector socket during shipping and handling of the computer.
The use of screws to removably secure the extension card to the cage structure suffers from several disadvantages. For example, during initial installation of the extension card within the cage structure one or more of the retaining screws can easily fall into the typically crowded interior of the computer, thereby creating a sometimes frustrating situation that may potentially damage the computer motherboard. Additionally, when a series of extension cards is installed at the factory, each individual connecting bracket is typically installed using an automated assembly machine. The installation of the screws is time consuming and, thus, contributes to appreciably increasing the overall assembly time for each computer in which extension cards are to be factory installed.
The use of such system also creates potential problems and inconveniences for the purchaser of the computer and/or technicians that subsequently work on the extension card portion of the computer. For example, when subsequently adding or exchanging extension cards, the technician or computer owner must unscrew the connecting bracket in place and then re-insert the removed screw into the connecting bracket on the added extension card.
Each time this task is carried out, there is the potential for dropping one or more of the individual retaining screws into the computer system. Additionally, when the computer system is being analyzed for a problem, it is often necessary to remove all of the extension cards to isolate the problem.
Thus, to install extension and so-called riser cards within the housing, it has previously been necessary to individually position each card over and separately connect each card to the motherboard using appropriate cable connectors with the extension cards in a horizontally-stacked array. In such systems, the riser card is perpendicular to the motherboard and a grounding connection for the extension riser card is also installed.
In another conventional desk top computer construction, the extension cards are individually connected in vertical orientations to the motherboard without a separate riser card. The present invention particularly relates to the second type of extension cards wherein they are connected in vertical orientation to the motherboard.
Nevertheless, whether of the horizontal or vertical type, the installation techniques required for such extension card tend to be laborious and time consuming thereby undesirably increasing the overall fabrication cost associated with the computer. As previously mentioned, they also lead to adversely affect the serviceability and upgradability of the computer since subsequent access to the motherboard requires that the extension cards be individually disconnected and removed to gain access to the motherboard portion which they overlie.
It can readily be seen from the foregoing that it would be highly advantageous from serviceability, upgradability and manufacturability standpoints to provide improved apparatus and associated methods for removably mounting operating components such as extension cards on a computer motherboard.
Typically, computer chassis designs allow the installation and removal of extension cards in the same direction as the supporting card guides are oriented. One type of chassis design which allows this is where the extension cards are plugged directly into the motherboard rather than a daughter card extending perpendicularly from the motherboard. In this type of design, a card guide that is either a separate part or integral to the chassis can be oriented to allow unimpeded insertion of a full-length extension card.
In another common chassis design, the extension cards plug into a riser card, which is fixed in the system. Once installed, the extension cards are parallel to the motherboard. An opening defined in one side of the chassis allows the extension cards to be installed and removed.
Since the riser card is fixed within the chassis, and is typically not removed in this type of design, the card guide can once again be oriented to allow unimpeded insertion of the full-length card. The drawback of this design is that typically all the extension cards must be removed individually before the user can remove the motherboard or access the area of the motherboard beneath the extension cards.
Some manufacturers have worked to improve the serviceability and accessibility of the motherboard by implementing a card cage chassis design. In such designs, the riser card is mounted within a removable card cage. Extension cards can then be installed when the card cage is either installed or removed from the system. The card guides are actually part of the card cage and therefore travel with the riser card and extension card. Once again, there is no impediment when removing from the system. Such system suffers from numerous drawbacks.
Accordingly, there exists a need for a card insertion and removal system of improved construction.